Asymptomatic bradycardia after first fingolimod dose in a pediatric patient with multiple sclerosis - a case report.

Fingolimod is currently approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of pediatric patients with relapsing-remitting multiple sclerosis (RRMS). However, transient asymptomatic bradycardia with treatment initiation has been reported in a small population of predisposed patients, which may be a result of short-term activation and internalization/desensitization of the G-protein-gated potassium channel IKACh on the atrial myocyte membrane. Asymptomatic bradycardia, with or without atrioventricular block, is generally self-limiting and has been reported within the first 6 h of administration of the first oral dose of fingolimod. Therefore, patients initiating fingolimod treatment are monitored for this initial period to identify any changes in their electrocardiogram and heart rate that may require further treatment. Here, we report a case of a 17-year-old female with RRMS who received her first fingolimod dose and showed asymptomatic bradycardia that resolved without treatment.